KR20140037140A - Method and device for operating a brushless motor - Google Patents

Abstract

에서 전력 반도체 스위치들 (2) 을 연속적으로 개방하도록 스위칭 오프된다. 모터 각 위치 센서 (6) 는 전력 경로 외부에 위치되고, 인버터 (3) 에서의 스위치 (5) 가 결함성이더라도 전력 반도체 스위치들 (2) 을 신뢰성있게 개방할 수 있다.The present invention relates to a method of operating a brushless electric motor, the windings of which are controlled by an inverter using six switches, wherein the inverter comprises three outputs associated with the windings of the electric motor, respectively The power semiconductor switch of the inverter is arranged between the outputs of the inverter and the windings, and is provided with a detection unit for detecting defective switches, a unit for measuring voltage at the outputs of the inverter, and a motor angular position sensor for determining the motor angular position. . The invention further relates to a device for operating a brushless electric motor. In order not to damage the power semiconductor switches, according to the invention, the inverter 3 has no additional power after the fault switch 5 is detected, the windings U, V, W of the electric motor 1. Motor angular position sensor 6 is not introduced into the

Is switched off to open the power semiconductor switches 2 continuously. The motor angular position sensor 6 is located outside the power path and can reliably open the power semiconductor switches 2 even if the switch 5 in the inverter 3 is defective.

Description

METHOD AND DEVICE FOR OPERATING A BRUSHLESS MOTOR}

The present invention relates to a method of operating a brushless electric motor, the windings of which are controlled by an AC converter using six switches, wherein the AC converter comprises three outputs assigned to the windings of the electric motor. The power semiconductor switch, in each case, is arranged between the outputs of the AC converter and the windings, the detection unit for detecting faulty switches, the unit for measuring voltage at the outputs of the AC converter, and the motor position angle. A motor position angle sensor for determining is provided. The invention further relates to a device for operating a brushless electric motor.

AC converters that control brushless motors generally include six switches. In the case of a fault, each switch is in principle two different properties: non-conductive (ie in the open switching position, the switch performs a blocking function), or conductive (ie in the closed switching position) May perform a blocking function). Conductive fault switches are also known as short circuits. In addition, especially in safety-related applications, it is important to switch the electric motor to an emergency mode very quickly or to switch off the electric motor immediately.

In contrast to mechanical relays, the use of power semiconductor switches depends on the magnitude of the load current and the inductance of the load when the inductive loads are switched off, resulting in the power semiconductor switch being destroyed at the moment the inductive load is switched off and consequently This is hampered by the disadvantage that it is possible for the power semiconductor switch to release an amount of energy of such magnitude that it can no longer fulfill its role. In particular, when power semiconductor switches for brushless motors are used in applications where safety is important and where it is necessary to switch off the motor in the power circuit to provide protection, damage to the power semiconductor switches is avoided. It is necessary to avoid. One safety-critical application is the use of brushless electric motors in the electromechanical steering arrangement of a vehicle.

For these types of applications where the induced energy in the load circuit exceeds the acceptable absorption capacity of the power semiconductor switch, due to its configuration, it includes a significantly larger absorption capacity compared to the power semiconductor switches currently available on the market. It is known to use a mechanical relay instead. Although the mechanical relay boosts and thus can be activated at any time, the switching-off energy that inevitably occurs when switching inductive loads in the dark flow has very serious availability problems as a mechanical system. A further possibility is to circumvent the amount of energy generated during the switching off of an inductive load, for example an energy sink, such as a suppression diode, which reduces the load on the power semiconductor switch.

It is therefore an object of the present invention to provide a method and device in which damage to semiconductor switches is reliably avoided during switching off inductive loads.

This object is achieved due to the features of the independent claims. The AC converter switches off in such a way that after the detection of the faulty switch, no power is introduced into the windings of the electric motor and the motor position angle sensor continuously opens the power semiconductor switches at the predefined motor position angle. do.

Advantageous developments are apparent in the dependent claims.

From this, in a preferred embodiment of the method according to the invention, the motor position angles are in each case assigned to the windings and to the power semiconductor switch and that the assigned power semiconductor switches are chosen in such a way that they are not damaged during the opening process. Entails being provided. For this purpose, the motor position angles are selected such that the prevailing drain current in the power semiconductor switches is zero, nearly zero, or negative.

The instantaneous values of the drain currents that cause the inductive loads to switch off without damaging the power semiconductor switches are provided that are deterministically dependent on the motor angle, which is dominant in the power semiconductor switches. It is important that the method is not absolutely necessary to monitor the phase currents directly using the measurement technique, since the information required for that purpose can be derived from the measured motor angle.

The object is also that the AC converter, by means of a microcontroller after the detection of the faulty switch, is no longer introduced into the windings of the electric motor and the motor position angle sensor is continuously connected to the power semiconductor switches at a predetermined motor position angle. Achieved by a device switched off in such a way that it is designed to open.

In a particularly advantageous development of the claimed subject matter, the motor position angle sensor is adapted to assign motor position angles to the winding and the power semiconductor switch of the winding in each case, and that the assigned power semiconductor switches are not damaged during the opening process. Is designed to select the motor position angles. The motor position angle sensor is designed to select motor position angles such that the dominant drain current in the power semiconductor switches is zero, nearly zero, or negative.

Power semiconductor switches are provided that are implemented as power MOSFET transistors.

A further advantageous development of the subject matter of the present invention provides that the unit for detecting faulty switches and the unit for measuring voltage at the outputs of the AC converter are integrated into the microcontroller.

The invention is further described below using two exemplary embodiments in conjunction with the accompanying drawings.

1 shows a schematic diagram of an AC converter and windings of a brushless electric motor according to the prior art.
2A shows a diagram with motor position angles for switching off the assigned power semiconductor switch in the case of a positive rotational direction of the electric motor.
2b shows a diagram with motor position angles for switching off the assigned power semiconductor switch in the case of a negative rotational direction of the electric motor.
3 shows a schematic diagram corresponding to FIG. 1 according to the prior art.
4 shows a schematic diagram of a device according to the invention.
5 shows a schematic circuit diagram of a second exemplary embodiment.

1 schematically shows a brushless electric motor 1, the windings U, V, W of which are controlled by an AC converter 3. For this purpose, the AC converter 3 comprises six switches 5, wherein the upper switches 5 in FIG. 1 are assigned to a positive supply voltage and the lower switches 5 in FIG. 1. ) Is assigned to the negative supply voltage. As further evident from FIG. 1, the voltage tapping points 17, 18, 19 are located between the upper switches 5 assigned to the positive supply voltage and the lower switches 5 assigned to the negative supply voltage. At the voltage tapping points, the dominant voltage in the windings U, V, W is tapped and the voltage is supplied to the unit 11 provided for measuring the voltage. The measurement results from the unit 11 provided for measuring the voltage are, on the one hand, a microcontroller that controls the switches 5 and on the other hand evaluates the information generated by the unit 11 provided for measuring the voltage. It is supplied to the controller 4. In addition, the detection unit 10 is provided for detecting the defective switches 5. The information generated by the detection unit 10 is similarly supplied to the microcontroller 4 for evaluation. The power semiconductor switches 2 are arranged in phase lines leading to the windings U, V, W.

In one embodiment, in practice, the switches 5 are formed by semiconductor switches and / or transistors or MOSFET transistors. In practice, the detection unit 10 is implemented as a bridge driver and applies a voltage to the switches 5 implemented as a transistor, which detects whether the switching position of the transistor is changing. In practice, the unit 11 provided for measuring the voltage at the voltage tapping points 17, 18, 19 is implemented as a voltage divider, which determines the duty cycle of the pulse width modulated voltage. The duty cycle corresponds to the quotient arising from the pulse duration and the period duration.

Each switch 5 may, in principle, comprise two different types of faults, or rather, if it is a fault, each switch is essentially one of two subsequently described states: ie non Conductive defects (ie, in the open switching position, the switch performs a blocking function); Or a conductive defect (ie, in a closed switching position, the switch performs a blocking function). The conductive defect switch 5 is also known as a short circuit.

In particular, in safety-related applications such as in electromechanical steering devices, it is important to switch the electric motor 1 to the emergency mode very quickly or to switch off the electric motor immediately. Failure of the conductive fault switch 5 results in increased steering torque in the event of a fault because the driver of the vehicle moves the electric motor 1 in generator mode and induces a current which is immediately counteracting the steering movement on the steering wheel. do. This torque against the direction of rotation of the driver of the vehicle is subsequently known as the braking torque. The braking torque, which depends on the rotational speed, is generated in the synchronous machine which is permanently excited due to the short circuit in the AC converter 3. The conductive defective switch 5 causes a short circuit to occur over the motor windings U, V, W as a result of the induction.

) 의 윈도우에서 개별적으로 스위칭 오프되며, 결과로서, 각각 영향받은 권선 (U, V, W) 을 통해 흐르는 임의의 전류는 할당된 전력 반도체 스위치 (2) 를 손상시키지 않는다. 전력 반도체 스위치들 (2) 은 전력 MOSFET 트랜지스터들로서 구현되며, 제로, 네거티브 또는 낮은 포지티브인 드레인 전류 (I_D) 의 단기 값은 손상되지 않는다. 이러한 방법의 특성은, 적절한 모터 위치각 윈도우들 (

) 이 AC 변환기 (3) 에서의 전도성의 결함 스위치 (5) 의 위치와 무관하게 항상 일정하게 유지되고, 오직 전기 모터 (1) 의 회전 방향에만 의존한다는 것이다. 따라서, 마이크로제어기 (4) 에 의한 수용가능한 모터 위치각 윈도우들 (

) 의 검출에 의해 의도적인 방식으로 개별 전력 반도체 스위치들 (2) 을 스위칭 오프하는 것은 충분하다. 모터 위치각 (

) 은 모터 위치각 센서(6) 를 이용하여 검출된다. 브러시리스 전기 모터 (1) 를 제어하기 위해 모터 위치각 (

) 을 검출하는 것이 필요하다. 따라서, 본 명세서에서 설명된 방법을 구현하기 위해 추가적인 센서가 필요하지는 않다.The phase connectors of the electric motor 1 are connected to the outputs of the AC converter 3 which are driven by the power semiconductor switches 2 for the purpose of using the brushless electric motor 1. The purpose of this arrangement is to disconnect the electric motor 1 in the event of a defect in the AC converter 3 and consequently to disconnect the electric motor from the previously described braking torque. This is also described as a safe shutdown. After a defect in the AC converter 3 is detected by the microcontroller 4, the AC converter 3 is initially switched off, ie the switches 5 are opened so that the electric power is no longer supplied. ) Is not introduced. If the electric motor 1 is still in its rotational state by inertia or by a drive from the outside, the current peak is the electric motor 1 by means of the switch 5 and parasitic diodes assumed to be conductively defective. The rectification of the induced voltage of cyclically increases in the AC converter 3, and the current peak generates unwanted braking torque. The process of switching off the power semiconductor switches 2 in the phase lines prevents this. In order to prevent damage to the power semiconductor switches 2 as a result of an unacceptably high inductive amount of energy from the electric motor 1, the power semiconductor switches are provided with defined motor position angles (

Are individually switched off in a window, and as a result, any current flowing through each of the affected windings U, V, W does not damage the assigned power semiconductor switch 2. The power semiconductor switches 2 are implemented as power MOSFET transistors, and the short term value of the drain current I _D , which is zero, negative or low positive, is not damaged. The nature of this method is that the appropriate motor position angle windows (

) Is always kept constant regardless of the position of the conductive defect switch 5 in the AC converter 3 and depends only on the direction of rotation of the electric motor 1. Thus, acceptable motor position angle windows by the microcontroller 4 (

It is sufficient to switch off the individual power semiconductor switches 2 in an intentional manner by detecting. Motor position angle (

Is detected using the motor position angle sensor 6. Motor position angle (to control the brushless electric motor 1)

) Is necessary. Thus, no additional sensor is needed to implement the method described herein.

) 은 AC 변환기 (3) 에서의 전도성의 결함 스위치 (5) 의 위치에 의존하지 않는다. 적절한 모터 위치각들 (

) 은 실제로 일정하게 유지된다. 이러한 상관이 도 2 에 도시된다.As mentioned previously, suitable motor position angle windows (

) Does not depend on the position of the conductive defect switch 5 in the AC converter 3. Proper motor position angles (

) Is actually kept constant. This correlation is shown in FIG.

로서 정의된다면, 전원이 끊긴 각 윈도우들은 간격들

=[300°; 60°],

=[60°; 180°] 및

=[180°; 300°] 에서 3개 위상으로 놓인다. 이들 값들은, 모터의 기계적 회전 속도 (N) 로 인해 발생하는 전기적 시간 주기 (TPER=1/(N*폴 쌍들의 수)) 가 위상 임피던스 (τPH=L/R) 의 시상수들과 비교하여 작게 유지되며 따라서 모터에서의 전류들 및 전압들이 대략적으로 부합하는 방식으로 여전히 확장하는 이상화된 비율들을 위해 적용한다. 하지만, 실제로, 이러한 이상화된 비율들은 자동으로 생성되지 않는다. 따라서, 모터 특성 변수들 및 고려될 최대 회전 속도에 의존하여, 모터 위치각 윈도우는 120° 미만이 될 수 있고, 부가적으로, 도 2a 및 도 2b 에 도시된 바와 같이, 회전의 방향에 의존하게 될 수 있다는 것이 고려되어야 한다. 모터 위치각 윈도우들의 경계 값들은 특정 어플리케이션에 대하여 디멘져닝되어야 한다. 하지만, 이는, 미리 정의된 모터 위치각 윈도우 내의 유도 부하들을 스위칭 오프하는 기본적인 방법에 있어서 어떠한 변경들도 야기하지 않는다.In the case of a three-phase BLDC motor, the motor position angle windows generated by the induced voltages and caused by the conductive fault switch 5 in the AC converter 3 are zero in individual phases, theoretically up to 120 °. Width. The motor angle is at a point where the induced voltage of the motor 1 driven from the outside in phase U is at its maximum.

If defined as

= [300 °; 60 °],

= [60 °; 180 °] and

= [180 °; 300 °] in three phases. These values show that the electrical time period (TPER = 1 / (number of N * pole pairs)) caused by the mechanical rotational speed N of the motor is small compared to the time constants of the phase impedance τPH = L / R. This applies for idealized ratios that are maintained and thus still extend in a way that the currents and voltages in the motor are approximately matched. In practice, however, these idealized ratios are not generated automatically. Thus, depending on the motor characteristic variables and the maximum rotational speed to be considered, the motor position angle window can be less than 120 ° and additionally, depending on the direction of rotation, as shown in FIGS. 2A and 2B. Should be considered. The boundary values of the motor position angle windows must be dimensioned for a particular application. However, this does not cause any changes in the basic way of switching off the inductive loads within the predefined motor position angle window.

) 은 불행히도 각각의 어플리케이션에 대하여 동일하지 않다. 회전이 외부로부터 생성되는 모터 샤프트의 회전은, 실제로 항상, 3위상 브러시리스 전기 모터 (1) 에 대한 3위상 시스템에 대응하여 각각의 경우 서로에 대하여 120° 로 변위된 사인파 형상의 진행을 갖는 3개의 유도 전압들을 생성하며, 그 후, 결과적으로, 이들은 전류 피크들의 증대를 유도한다. 하지만, 이러한 전류 피크들은 유도 전압들에 대하여 부합하는 방식으로 확장하지 않으며, 오히려, 모터 위상들 (U, V, W) 의 복소 임피던스의 결과로서, 첫째로 시간 지연을 경험하고 둘째로 AC 변환기 (3) 에서의 단락 회로와의 외부 경계 조건의 결과로서 형태에 있어서의 왜곡을 경험한다. 더욱이, 전류 피크들은 증가하는 모터 회전 속도 (N) 에 따라 확장하며, 모터 위치각 윈도우들 (

) 은 대응하여 더 작아지게 된다. 결국, 모터 위치각 윈도우들 (

) 을 결정하는 프로세스는, 이용되고 있는 전기 모터의 특성 값들 및 또한 고려될 최대 회전 속도 (N) 를 고려하는 측정 작업이다. 전력 반도체 스위치들 (2) 에 대하여 수용가능한 에너지의 양은 또한 하나의 기준이며, 이러한 에너지의 양이 클수록, 스위칭 오프 프로세스 동안 여전히 존재할 수 있는 상전류의 단기 값도 커지며, 이는 모터 위치각 윈도우 (

) 를 최대화할 경우에 유용하다.Motor Position Angle Windows for Switching Off Process (

) Is unfortunately not the same for each application. The rotation of the motor shaft, in which the rotation is produced from the outside, is in fact always always three, having a sinusoidal shape displacement displaced by 120 ° with respect to each other in correspondence with the three phase system for the three phase brushless electric motor 1. Induction voltages, and as a result, they induce an increase in current peaks. However, these current peaks do not extend in a consistent manner with respect to induced voltages, but rather, as a result of the complex impedance of the motor phases (U, V, W), firstly they experience a time delay and secondly, the AC converter ( 3) experience distortion in the form as a result of external boundary conditions with a short circuit in. Moreover, the current peaks expand with increasing motor rotational speed N, and the motor position angle windows (

) Becomes correspondingly smaller. As a result, the motor position angle windows (

The process of determining) is a measurement task taking into account the characteristic values of the electric motor being used and also the maximum rotational speed N to be considered. The amount of energy acceptable for the power semiconductor switches 2 is also one criterion, and the greater this amount of energy, the greater the short-term value of phase current that may still be present during the switching off process, which results in a motor position angle window (

This is useful for maximizing).

) 는 300° 로부터 60° 까지 이르고, 모터 위치각 윈도우 (

) 에 대응하는 권선 (V) 에 대해서는 60° 로부터 180° 까지 이르며, 권선 (W) 에 대하여 모터 위치각 윈도우 (

) 는 180° 로부터 300° 까지 이른다. 이는 높은 L/R 비율을 갖는 모터들에 대한 모터 위치각들 (

) 의 미리 간략히 설명된 원리 축약들을 포함하며, 높은 회전 속도들은 본 명세서에서 음영 표시된 블록들로서 도시된다.2A and 2B, the idealized ratios in the case of a motor with a very small ratio of phase induction to phase resistance are shown as successive blocks of black color. In these ideal conditions, the motor position angle window for the winding U (

) Ranges from 300 ° to 60 °, and the motor position angle window (

60 ° to 180 ° with respect to winding V corresponding to

) Ranges from 180 ° to 300 °. This means that the motor position angles for motors with a high L / R ratio (

The principle abbreviations described previously in brief, wherein high rotational speeds are shown herein as shaded blocks.

) 의 함수로서 개방된다. 이러한 미리 공지된 배열들의 경우, 위치각 센서 (6) 는 그 출력 신호들을 마이크로제어기 (4) 로 공급하지 않는다. 마이크로제어기 (4) 는 전력 반도체 스위치들 (2) 을 작동시킨다.An example corresponding to FIG. 1 is selected in FIG. 3. The electric motor 1 is operated by a converter 3 by open or closed switches 5, shown as a common block in FIG. 3. The power semiconductor switches 2 are arranged between the switches 5 and the windings U, V, W of the electric motor 1. As already described with reference to Figs. 1 and 2, the power semiconductor switches 2 have the motor position angles in the case of a failure.

Open as a function of In the case of such known arrangements, the position angle sensor 6 does not feed its output signals to the microcontroller 4. The microcontroller 4 operates the power semiconductor switches 2.

In the case of a conductive defective switch 5 in the AC converter 3, there is also a risk of the microcontroller 4 being destroyed as a result of the failure. If the microcontroller 4 is a faulty switch 5 in the AC converter 3, there is a complex decoupling between the AC converter 3 and the microcontroller 4 so that it is always possible to safely open the power semiconductor switches 2. need.

), 모터 속도 및 회전 방향과 같이 전력 반도체 스위치들 (2) 의 안전한 개방을 위해 필요한 정보 모두가 이러한 모터 위치각 센서 (6) 에 이미 존재하기 때문에 특히 유리하다.The idea of the present invention is therefore that the power semiconductor switches 2 are no longer operated by the microcontroller 4 but instead are directly operated by the motor position angle sensor 6. Thus, in the case of the device shown in FIG. 4, signals which reliably open the power semiconductor switches 2 are generated directly from the motor position angle sensor 6. This is the motor position angle (

), It is particularly advantageous because all the information necessary for the safe opening of the power semiconductor switches 2, such as motor speed and direction of rotation, already exists in this motor position angle sensor 6.

The idea essential to the invention is that the initiation for opening of the power semiconductor switches 2 is no longer in the microprocessor 4 but instead in the motor position angle sensor 6 which provides the motor angle and motor speed. This solution is independent of the microprocessor 4 and can therefore be very cost-effectively integrated into a system that provides motor angle and motor speed.

As the motor rotation speed increases, each window for safely opening the power semiconductor switches 2 becomes smaller, and additionally, the higher rotation speed of the electric motor 1 becomes smaller each window becomes smaller. Also means pass more quickly. For this reason, at very high rotational speeds, very accurate signals with short latency times are necessary for the safe opening of the power semiconductor switches 2, and as a result, only very very upon opening of the power semiconductor switches 2. Only small or negative motor currents continue to exist. Thus, generating signals for the opening of the power semiconductor switches 2 directly from the motor position angle sensor 6 providing the motor angle and motor speed allows this arrangement to allow extremely high update rates with very short processing time. It is very advantageous. Very short processing time is achieved, in particular, due to the fact that motor angle information and motor speed information should not be sent to the microprocessor 4.

Thus, the safe opening of the power semiconductor switches 2 in the case of direct operation from the motor position angle sensor 6 providing the angle is a higher rotational speed than is possible with the operation from the microprocessor 4. Is possible in the field.

) 내에서 전력 반도체 스위치들 (2) 을 개별적으로 스위칭 오프하기 위한 모터 위치각 (

) 의 사용은, 도 4 에 도시된 실시형태에 비교하여 변경없이 유지된다.FIG. 5 shows a second embodiment comprising the topology of the power semiconductor switches 2 as a “star-point switch”, wherein the power semiconductor switches 2 are eventually implemented as power MOSFET transistors and the motor phases ( The end connectors of U, V, and W are connected to the "star point". Appropriate motor positioning angle windows (

Motor position angle for individually switching off the power semiconductor switches 2 within

) Is maintained without change as compared to the embodiment shown in FIG. 4.

The application of the described method is that in a system for operating a brushless electric motor 1, the maximum possible amount of inductive energy generated due to the magnitude of the motor inductances and currents of this type of system is available and / or Or even if it exceeds the absorption capacity of economically just power semiconductor switches, it makes possible to use the power semiconductor switches 2 as a safety feature. Thus, for a variety of reasons: namely, due to wear characteristics, sensitivity to moisture, varying contact characteristics and lack of reliability, etc., it is possible to avoid the use of undesired mechanical relays and also to suppress diodes or currents. It is sometimes possible to use a more desirable solution due to its configuration using power semiconductor switches without the need to introduce additional switching means for external energy absorption, such as devices for measuring.

Claims (10)

A method of operating a brushless electric motor (1)
The windings U, V, W of the electric motor are controlled by an AC converter 3 using six switches 5, the AC converter 3 windings of the electric motor 1. Three outputs 17, 18, 19 assigned to (U, V, W), the power semiconductor switch 2 in each case outputs 17 of the AC converter 3; 18, 19 and a detection unit 10 arranged between the windings U, V, W, for detecting the defective switches 5, outputs 17, 18, 19 of the AC converter 3 Unit 11 for measuring the voltage at, and the motor position angle (

Motor position angle sensor 6 is provided,
The AC converter 3, after detection of the faulty switch 5, no power is introduced into the windings U, V, W of the electric motor 1 and the motor position angle sensor 6 Is the predefined motor position angle (

A method of operating a brushless electric motor, characterized in that it is switched off in such a way as to open the power semiconductor switches (2) continuously. The method of claim 1,
The motor position angles (

) Is in each case assigned to the windings U, V, W and to the power semiconductor switch 2 of the winding and selected in such a way that the assigned power semiconductor switches 2 are not damaged during the opening process. And a brushless electric motor. 3. The method according to claim 1 or 2,
The motor position angles (

) Is selected such that the dominant drain current (I _D ) in the power semiconductor switches (2) is zero or almost zero. 3. The method according to claim 1 or 2,
The motor position angles (

) Is selected such that the dominant drain current (I _D ) in the power semiconductor switches (2) is negative. 5. The method according to any one of claims 1 to 4,
The motor position angles (

) Is defined in dependence on the rotational direction of the electric motor (1) and not on the position of the fault switch (5). A device for operating the brushless electric motor 1,
The windings U, V, W of the electric motor are controlled by an AC converter 3 using six switches 5, the AC converter 3 windings of the electric motor 1. Three outputs 17, 18, 19 assigned to (U, V, W), the power semiconductor switch 2 in each case outputs 17 of the AC converter 3; 18, 19 and a detection unit 10 arranged between the windings U, V, W, for detecting the defective switches 5, outputs 17, 18, 19 of the AC converter 3 Unit 11 for measuring the voltage at, and the motor position angle (

Motor position angle sensor 6 is provided,
The AC converter 3 is no longer introduced into the windings U, V, W of the electric motor 1 by the microcontroller 4 after the detection of the faulty switch 5 The motor position angle sensor 6 has a predefined motor position angle (

A device for operating a brushless electric motor, characterized in that it is switched off in such a way that it is designed to open the power semiconductor switches (2) continuously. The method according to claim 6,
The motor position angle sensor 6 is provided with the motor position angles (

) Is in each case assigned to windings U, V, W and the power semiconductor switch 2 of the winding, and the motor position angle so that the assigned power semiconductor switches 2 are not damaged during the opening process. Device for operating a brushless electric motor, characterized in that it is designed to select ones. 8. The method according to claim 6 or 7,
The motor position angle sensor 6 has the motor position angles () such that the dominant drain current I _D in the power semiconductor switches 2 becomes zero, nearly zero, or negative.

A device for operating a brushless electric motor. 9. The method according to any one of claims 6 to 8,
The device for operating a brushless electric motor, characterized in that the power semiconductor switches (2) are implemented as power MOSFET transistors. 10. The method according to any one of claims 6 to 9,
The unit 10 for detecting the faulty switches 5 and the unit 11 for measuring voltage at the outputs 17, 18, 19 of the AC converter 3 are integrated in the microcontroller 4. A device for operating a brushless electric motor, characterized in that.

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